#include  <iostream>
using  namespace  std;

int fun(int a[],int len,int m)
{
    if(m<0)
        throw "index < 0,underflow\n";
    if(m > len)
        throw "index > len,overflow\n";
    return a[m];
}
int main()
{
    int arr[5]={2,3,5,7,9};
    int x;
    cin>>x;
    try
    {
        cout<<fun(arr,5,x)<<endl;
    }
    catch(const char* msg)
    {
         cout<<msg;
    }
    cout<<"end!"<<endl;
    return 0;
}
